1. Field of the Invention
The present invention relates generally to a Zero Insertion Force (ZIF) socket electrical connector, and particularly to a ZIF socket connector having an improved contact.
2. Description of Related Art
Zero Insertion Force (ZIF) socket type electrical connectors have been widely used for connecting electronic devices such as central processing unit (CPU) packages to, for example, a printed circuit board. A socket connector generally comprises an insulative housing or base in which a plurality of bores or channels is defined, each receiving and retaining a conductive contact. Each bore forms an interior space that is large enough so that the contact that is received in the bore occupies only a fraction of the space. An extra free gap is thus left in the bore for receiving a corresponding pin of the electronic device therein with substantially no resistance. Once the pin is placed into the extra free gap, the electronic device is moved with respect to the housing, driving the pin into engagement with a resilient arm of the contact. The arm is then deflected by the pin, ensuing a stable engagement between the pin and the arm.
Some of the conventional contacts designed for such purposes have a single arm. Examples are described in U.S. Pat. Nos. 5,052,101 and 5,489,218. A disadvantage associated with the single-armed contact is that the pin is subjected to a moment caused by the resilient force of the single arm. In addition, due to the small size of the contact and the high density of the contacts arranged in the housing, the pins of the electronic device must be perfectly aligned with the corresponding contacts before the pins are driven to engage the arms of the contacts. This is in general very difficult to accomplish.
Others conventional contacts have a design with two arms wherein the two resilient arms extend from opposite edges of a substantially rigid base section. U.S. Pat. Nos. 3,955,869 and 5,299,950 describe such contacts. Generally, the arms of such contacts are opposed to one other and define a gap of a distance generally smaller than a diameter of the corresponding pin of the electronic device. When the pin is driven into the gap between the arms, the arms are deflected away from each other to accommodate the pin. The axes about which the arms deflect pass through a junction between the corresponding arm and the base. The axes are changelessly located at the junctions. The gap, therefore, is invariable. So changes in the diameter of the pin, or in the thickness of the contact, produces undue pressure between the arms and the pin, and thereby affects the electrical and mechanical performance of the connector. Furthermore, rigidity of the junction affects the deflection of the arm. When the rigidity is increased, the deflection is reduced. When the rigidity is reduced, the deflection is increased. A new design is required to improve an adaptability of a gap between the arms.
A contact structure of an electrical connector is desired to alleviate or even eliminate the above-discussed problem.
Accordingly, an object of the present invention is to provide a contact of an electrical connector comprising two arms designed such that a distance between the arms is adjustable for engaging with a pin of the electronic device inserted.
To achieve the above object, a contact in accordance with the present invention, comprises a base portion having upper and lower edges. Two support portions extend from an upper edge of the base portion and are spaced apart from each other. A pair of arms separately protrude from the support portions. A gap is defined between the arms. Each arm is spaced from the upper edge of the base portion a different distance, whereby the arms are staggered with respect to each other. At least a recess is defined in an upper end of each support portion adjacent to a junction between the arm and the support portion. A soldering portion extends from the lower edge of the base portion and is adapted to be soldered to an external device.